Abstract: Process for cooling and crystallizing solid melamine from the gaseous phase or from melamine melts as they develop in technical processes used to produce melamine, characterized in that the melamine-containing process gases or melamine melts are introduced into a liquid, organic phase at high pressure, said phase comprising polyvalent alcohols such as ethylene glycol, glycerine or their homologous series or of amines such as ethanol amines. Mixtures of both groups of compounds are suitable as well. The advantage of this process is that the hot melamine is cooled very quickly without forming thermal decomposition products and that during quenching no reaction of the melamine with the solvent occurs as in the case with a water quench.

Abstract: Process for cooling and crystallizing solid melamine from the gaseous phase or from melamine melts as they develop in technical processes used to produce melamine, characterized in that the melamine-containing process gases or melamine melts are introduced into liquid, organic phase at high pressure, said phase comprising polyvalent alcohols such as ethylene glycol, glycerine or their homologous series or of amines such as ethanol amines or a mixture of both groups. The advantage this process is that the hot melamine is cooled very quickly without forming thermal decomposition products and that during quenching no reaction of the melamine with the solvent occurs, the formation of higher deammoniation products such as melam and melem is prevented and higher deammoniation products of the melamine such as melam and melem, are partially converted back into melamine.

Abstract: A method for purifying melamine comprising impurities like ureido-melamine, oxotriazines, melam, melem, comprises the step of putting into contact at a temperature comprised between 340° C. and 410° C. and at a pressure comprised between 8 and 17 MPa a melamine melt with a bed of a catalyst thus obtaininig melamine with a purity of at least 99%.

Abstract: A method for purifying melamine comprising impurities like ureido-melamine, oxotriazines, melam, melem, comprises the step of putting into contact at a temperature comprised between 340° C. and 410° C. and at a pressure comprised between 8 and 17 MPa a melamine melt with a bed of a catalyst thus obtaining melamine with a purity of at least 99%.

Abstract: In the preparation of ammonium carbamate by reacting ammonia with carbon dioxide, the reactants are introduced into a layer of ammonium carbamate which is kept in the fluidized state by gaseous ammonia or carbon dioxide. The temperature is kept below 25.degree. C. by removing the heat of reaction.

Abstract: Spherical refining catalysts containing cobalt and/or nickel together with molybdenum on aluminum oxide are prepared in closed mixers provided with mixing elements from spray-dried powders such as catalyst preparations or carriers using peptizing agents. The catalysts thus prepared have a bulk density much higher than that of extrudates of similar composition. Their surface and pore size distribution make them suitable for use in the catalytic refining of hydrocarbon fractions containing metal and asphalt, and particularly for refining vacuum distillates and residues from atmospheric distillation.

Abstract: Hard abrasion-resistant carbon is obtained from polymerized halohydrocarbons by elimination of hydrogen halide in a two-stage process carried out so that in the first decomposition stage, which is carried out at temperatures within the range from 140.degree. to 250.degree.C, a definite amount (not less than 5% by weight and not more than 50% by weight) of the total amount of hydrogen halide capable of being split off is removed. Appropriately shaped end products can be obtained by using raw materials having a globular, cylindrical or other shape. The carbon obtained is suitable as the stationary phase for chromatographic separation and analysis of mixtures.